High-tension circuit-breaking switch



June 13, 1961 F. PETERMICHL ETAL 2,988,622

HIGHTENSION CIRCUIT-BREAKING SWITCH 2 Sheets-Sheet 2 Filed March 9, 1959 I//////////I///////Az ?/I//////////////z?// m my w w? W Ema P5 WW. 2%

United States Patent C) HIGH-TENSION CIRCUIT-BREAKING SWITCH Franz Petermichl and Fritz Eiserlo, Kassel, Germany, as-

signors to Licentia Patent-Verwaltungs-G.m.b.H., Hamburg, Germany Filed Mar. 9, 1959, Ser. No. 797,949 Claims priority, application Germany Mar. 10, 1958 7 Claims. (Cl. 200-149) The invention relates to a high-tension switch with selfgenerated gaseous or vaporous extinguishing medium, in which the electric arc is drawn and blown Within a slotlike explosion chamber closed with exception of the outflow aperture for the switch gases.

One object of our invention is to produce a high-tension circuit-breaking switch in which the electric are formed upon opening of the switch always remains in a slot-like explosion chamber so that the performance of the switch can be improved considerably, and in which the electric arc is also capable of producing an effective stream of extinguishing medium in the interior of the extinguishing chamber which considerably assists in extinguishing the arc.

Circuit breakers with slot-like extinguishing chambers are already known which are built as load separators for low duty switching operations. However, in these switches the arrangement is not such that the arc remains continuously within the slot-like extinguishing chamber but is drawn out of the extinguishing chamber by a blade switch prong connected with the main breaking blade or knife and only partly blown by the extinguishing medium flowing out of the chamber, so that the switching efliciency remains only slight. The switch efficiency is improved if the arc remains within the slot-like extinguishing chamber during the entire extinguishing procedure and this chamber is closed except for the outflow aperture for the switch gases. A high-tension switch constructed in this manner is already known (Swiss Patent 186,066) but in this case the switch contacts shifted in thrust fashion are arranged on the bottom of the housing with the result that the electric arc has no opportunity of compressing the air stored in the extinguishing chamber and thereby producing a stream of extinguishing medium which effectively becomes operative as the arc approaches its zero state.

In order to improve considerably the switching efliciency of the switch in this respect, the high-tension switch according to the invention comprises switch contacts which are arranged within the extinguishing chamber in such a manner that the electric are drawn between them has an opportunity of deviating also in the direction away from the outflow aperture for the switch gases. In this instance, the arc can heat the volume of air contained in the extinguishing chamber, for example, below the switching contacts, so strongly that this medium is thus placed under pressure and forces the arc upwards and that, as the latter approaches its zero point, it produces a strong stream of extinguishing medium which causes a rapid deionization of the switching path. Theswitch contacts are preferably arranged at about half the height of the slotshaped portion of the extinguishing chamber, so that, in the case of breaking circuit, the electric are still moves always within the slot-shaped portion of the extinguishing chamber. Moreover, when the switch contacts are arranged in this manner, there is still suflicient space available for producing a strong stream of extinguishing medium.

In another embodiment of the switch according to the invention, an enlarged pressure chamber may be provided in the slot-shaped portion of the extinguishing chamber, from which the stream of extinguishing medium sets in when the arc pressure decreases. To enable this stream to be controlled it may be advisable to provide throttle points or barriers between the slot-shaped portion and the pressure chamber in the extinguishing chamber. The electric arc is extinguished in a particularly effective manner if the inner wall of the slot-shaped extinguishing chamber is lined in known manner with a material capable of emanating gas.

In a further embodiment of the switch according to the invention, the switch contacts can be arranged on the bottom of the extinguishing chamber, in which case the movable contact consists of a swivel knife or blade and the pressure chamber is located between the free end of this knife and the fixed contact. A plurality of grooves are then formed preferably in the side walls of the extinguishing chamber which allow the extinguishing medium to fiow out of the extinguishing chamber past the knife contact, whereas a two-armed lever rotatable between two fixed parts of the switch is provided as movable switch contact.

These and other features of the invention will become apparent from the accompanying drawings which illustrate by way of example several embodiments of the switch and in which FIGURE 1 is a longitudinal section through a hightension switch arrangement according to the invention, incorporating a slot-shaped extinguishing chamber;

FIGURE 2 being a cross section taken on line 22 of FIGURE 1;

FIGURE 3 is a longitudinal section of another embodiment of the invention similar to that illustrated in FIG- URE 1;

FIGURE 4 being a cross section taken on line 44 of FIGURE 3;

FIGURE 5 is a longitudinal section of yet another embodiment of the high-tension switch according to the invention;

FIGURE 6 being a longitudinal section taken on line 6-6 of FIGURE 5;

FIGURE 7 shows in longitudinal section another embodiment of the invention with swivel knife contact;

FIGURE 8 shows in cross section an extinguishing chamber of the high-tension switch according to the invention, equipped with a soot separator;

FIGURE 9 is a longitudinal section through an extinguishing chamber of the switch according to the invention, in which the walls are provided with grooves, and

FIGURE 10 is a horizontal cross section taken on line 10-10 of FIGURE 9;

FIGURE 11 shows in longitudinal section another embodiment of the invention with swivel contact;

FIGURE 12 is a sectional view of a portion of the side wall of the extinguishing chamber illustrated in FIGURE 11, and finally FIGURE 13 shows in longitudinal section an improved preferred form of construction of the switch according to the invention.

FIGURES 1 and 2 show a slot-shaped extinguishing chamber 1, in which the switch contacts 2 and 3 arranged substantially in the middle of the slot gap are constructed for thrust movement. On breaking the contacts, the resulting electric arc can deviate in the direction of the pressure chamber 4, thereby compressing the volume of air located therein which, in addition to the inherent electrodynamic force of the arc drives the are 5 on to the horn-like contact parts 6. Insulating parts 7 are provided in known manner in the outflow aperture of the pressure chamber and effect at the same time a throttling of the stream of extinguishing medium, thereby increasing the pressure in the chamber.

The stream of extinguishing medium passing out of I the chamber 4 can be regulated by a throttle point 8 or by barriers 9, as shown in FIGURES 3 and 4. Both the embodiments illustrated in FIGURES 1, 2, and 3, 4 enable a strong transverse blowing across the arc and the embodiment shown in FIGURES 3 and 4 possesses the advantage that an excess pressure is still present in the extinguishing chamber even after the arc has been extinguished as the current passes through zero, which excess pressure prevents a re-ignition of the arc. Moreover, the throttle point or barriers according to FIGURES 3 and 4 prevent the are from being driven into the pressure chamber by electrodynamic forces. It has been found that if this occurs the arc cannot be extinguished.

Another embodiment with swivel switch contact is illustrated in longitudinal section in FIGURE 5 and in cross section in FIGURE 6. In this embodiment the switch contacts 2 and 3 are also arranged in the center of the extinguishing chamber, whereby it is possible for the arc to place the volume of air in the enlarged pressure space 4 under strong pressure due to the breaking movement of the contacts in downward direction. A cooling device 11 with partition walls 12 is provided at the upper end of the extinguishing chamber. In addition, a filter 14 is arranged above the cooling device in.known manner, which filter is particularly advantageous when the chamber walls are lined with substances giving otf gases, in order to prevent these gases from forming explosive mixtures in the presence of air. It is true that by using the cooling device 11 the switch gases themselves are rendered non-conductive, so that no significant flame formation can be observed in the outlet apertures and no flashovers are caused; however, the switch gases may nevertheless have a temperature which is suflicient to ignite an explosive mixture with air. Such ignition in switches would lead to phase flashovers and consequently result in destruction by shortcircuit arcs. For this reason the filter 14 is provided which may, for example, consist of wire or textile fabric. It is advisable to use fabrics possessing relatively great mechanical strength, preferably metal wire, for the outer layers, and finer fabrics as inner layer of the filter. Such filters also effectively deaden the noise of the switch gases which otherwise escape with a detonating report when cutting out shortcircuits. Instead of the filter 14, a throttle point may be provided by which the outflow of the gas and consequently the pressure level in the chamber can be regulated in a particularly easy manner. This throttle point is designated by 15 in FIGURE 8, in which figure the walls of the slot-shaped portion of the extinguishing chamber are shown as being coated with material 16 adapted for emanating gas. Special conventional mixtures of synthetic substances such as melamine resin, urea resin and the like are suitable for such coating material.

' It is not absolutely essential that the switch contacts be located across the center of the extinguishing chamber to enable the arc to yield in the opposite direction to the outflow aperture. ,It may often be desirable to arrange the switch contacts near the bottom of the extinguishing chamber and to construct at least one of these contacts as a swivel knife between the free end of which and the fixed contact the pressure chamber is formed. A suitable form of construction is illustrated in FIGURE 7. Here the fixed contact is designated by 2 and the movable knife again by 3. An arc horn 6 is fitted on the stationary contact 2. On breaking the contacts, the arc can also place under pressure the volume of air located between the fixed contact and the free end of the knife so that the gases are not immediately blown towards the outflow aperture but first fill the pressure chamber 4 located below the broken line 10. Only then does the gas stream become preponderant in the direction towards the outflow aperture which terminates in the cooling devices 11. To prevent a shorting of the are through the metal plates of the cooling device, insulating 4 walls 12 are provided, the extensions of which serve at the same time for holding back the are within the slot-shaped portion of the extinguishing chamber. The movable switch contact 3 is operated by a shaft 13 which is guided in gas-tight bearings through the wall of the extinguishing chamber.

Since, when gas-emanating materials are used in the extinguishing chamber, a particularly strong stream is produced and this can also expand into the pressure chamber, particles of soot can easily deposit therein and detrimentally affect the insulation. To prevent this draw back, it is advisable to arrange in front of the pressure chamber a soot separator which is designated by 17 in FIGURE 8. The separation of the soot can be effected or improved by using a liquid such as water with the separator. A layer of such liquid is indicated at 18 in FIGURE 8. This liquid layer can serve at the same time for generating gaseous extinguishing medium to increase the extinguishing effect. The soot separator is provided with considerably enlarged rough or adhesive surfaces on which the soot particles stick.

I To lengthen the surface leakage current path between the contacts it is also expedient to provide in known manner a plurality of deep grooves in the slot-like portion of the extinguishing chamber. FIGURES 9 and 10 show an extinguishing chamber constructed in this manner. Here the walls are provided with deep grooves 18. Another possible way of ensuring against the effect of sooting consists in protecting in known manner the switch path against backfiring after complete break, by opening an insulated separating path connected up in series with the switch path.

FIGURES 11 and 12 show yet another embodiment of the invention in which recesses 19 are provided in the side walls of the extinguishing chamber 1. When the switch contacts 2, 3, are broken, these recesses enable the air or extinguishing gases under pressure to brush past and allow the switching-01f movement of the knife 3. As the knife 3 completely fills the cross sectional area of the extinguishing chamber, this knife would, without the recesses 19, prevent the air under pressure from flowing on in upward direction and the circuit-breaking movement of the knife could only be carried out by employing very strong driving means. To avoid recesses in the side walls, the. switch couldalso be so constructed that a two-armed lever rotatable between two fixed switch parts serves as movable switch contact. Such a construction is illustrated in FIGURE 13. The fixed switch parts are designated by 2 and 2' and the movable contact by 3. In this case, on the switch contacts being opened in the direction of the arrow, a pressure is exerted by the gases in the pressure chamber 4 on both surfaces of the two-armed lever, whereby the pressures counteract each other and the switching movement can be carried outwithou-t relatively strong driving means.

It. will be understood that this invention is susceptible to modification in order to adapt it to difierent usages and conditions, and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

' Whatwe claimis:

- 1. A high voltage circuit breaker with a self-generated arc-extinguishing gaseous medium, comprising in combination, an extinguishing chamber with a slot-shaped cross-section in the interior thereof having walls capable of giving ofi gas; a plurality of outflow apertures for the gaseous medium covering substantially completely one end of said chamber; a closed bottom at the other end of said chamber; separable breaker contacts within the slot shaped interior of the extinguishing chamber and abutting the side walls thereof; said breaker contacts so arranged as to form a path in the longer dimension of said chamber between their contact-making ends during the switching action and lying considerably above the closed bottom of the chamber but below said outflow aperture so as to 5 form a slot-shaped pressure chamber containing enough gaseous medium to be heated by the arc and to be directed to the breaker contacts after the arc passes through zero.

2. A switch according to claim 1, wherein the switch contacts are arranged at half the height of the slot shaped portion of the extinguishing chamber.

3. A switch according to claim 2, wherein an enlarged pressure chamber extends from the slotted portion of the extinguishing chamber opposite the outflow aperture.

4. A switch according to claim 3, wherein a throttle points interconnect the slotted interior and the pressure chamber of the extinguishing chamber.

5. A switch according to claim 1, wherein a filter composed of fine wire is arranged at the outflow aperture for the switch gases, and a cooling device positioned below said filter.

6. A switch according to claim 3, with knife contact capable of swinging in the direction towards the pressure chamber, there being a plurality of deep grooves provided in the side walls of the extinguishing chamber to allow the extinguishing medium to brush out of the pressure chamber past the knife contact.

7. A switch according to claim 1 wherein a filter coniposed of textile fabric is arranged at said outflow aperture, and a cooling device is positioned below said filter.

References Cited in the file of this patent UNITED STATES PATENTS 2,146,656 Skeats Feb. 7, 1939 2,155,276 Korndorfer Apr. 18, 1939 2,221,720 Prince Nov. 12, 1940 2,345,724 Baker et a1. Apr. 4, 1944 2,648,744 Strom et al Aug. 11, 1953 2,660,647 Rawlins Nov. 24, 1953 2,845,510 Biersack July 29, 1958 FOREIGN PATENTS 533,008 Great Britain Feb. 5, 1941 629,889 Germany May 15, 1936 729,915 Germany Jan. 5, 1943 763,510 Great Britain Dec. 12, 1956 877,391 France Sept. 7, 1942 889,064 France Sept. 20, 1943 

